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SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 54, NUMBER 7 



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DESCRIPTION OF A NEW SPECIES OF 

HIPPOPOTAMUS 

WITH FOUR PLATES 



BY 



GERRIT S. MILLER, Jr. 

Curator, Division of Mammals, U. S. National Museum 




(Publication 1927) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

March 28, 1910 









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D. OF D. 

910 



DESCRIPTION OF A NEW SPECIES OF HIPPOPOTAMUS 

By GERRIT S. MILLER, Jr., 
Curator, Division of Mammals, U. S. National Museum 

(With Four Plates) 

Two skulls of Hippopotamus in the U. S. National Museum, one 
from the Zambezi River, the other from Angola, differ noticeably 
from each other in important details of form. Hitherto the exact 
value of these characters could not be determined, owing to lack of 
material to illustrate the normal variation in individuals from one 
locality. The series of eight skulls from British East Africa col- 
lected by the Smithsonian African Expedition shows conclusively 
that individual variation in this genus is not unusually great, and 
that the Zambezian and Angolan specimens must be regarded as 
representing distinct species. In all essential characters the Zam- 
bezian skull agrees with those from British East Africa; these are 
for the present assumed to represent true Hippopotamus amphibius 
of the upper Nile. 1 The Angolan animal may be known as : 

HIPPOPOTAMUS CONSTRICTUS, sp. nov. 

Type. — Skull of immature male (m 3 not fully in place), number 
34787, U. S. National Museum; collected in Angola, Africa, by H. 
Chatelain. 

Diagnosis. — Skull in general like that of Hippopotamus amphibius, 
but rostral constriction deeper, dorsal surface of cranium more flat- 
tened, difference in level between anterior border of maxillary and 
of premaxillary more pronounced, and mandibular symphysis much 
shorter, its median length less than one-third length of mandible ; 
teeth smaller than in Hippopotamus amphibius, the transverse diam- 
eter of m 2 scarcely more than one-half that of palate. 

Skull. — The skull is throughout less robust than that of Hippo- 
potamus amphibius, a peculiarity equally noticeable in dorsal, ven- 
tral, or lateral aspect; depth at level of anterior border of orbit 
contained about 4 times in condylobasal length, instead of 3^ times, 
as in H. amphibius; rostral constriction very pronounced, its least 



1 This paper is the seventh dealing with the results of the Smithsonian 
African Expedition. 

Smithsonian Miscellaneous Collections, Vol. 54, No. 7 



2 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 54 

breadth contained nearly 7 times, instead of about 5 times in con- 
dylobasal length ; anterior portion of rostrum less expanded than 
in H. amphibius, the ratio of breadth across canines to zygomatic 
breadth about 7 J, instead of about 88; form of rostral expansion 
differing from that of the related species in the less forward exten- 
sion of maxillaries, so that level of canines is noticeably further 
behind that of anterior incisors, and the bases of the three teeth of 
each side lie nearly in a straight oblique line ; occipital region and 
dorsal surface of orbits much less elevated above level of median 
portion of frontals than in H. amphibius, the vertical diameter of 
orbit not conspicuously greater than transverse diameter; mandible 
with posterior portion less developed, both longitudinally and ver- 
tically, than in the related species, the ratio of height through coro- 
noid process to length (from articular process to front of alvedus 
of canine) about 60, instead of about 65 ; posterior border somewhat 
flattened immediately below articular process, the region of its 
greatest convexity at level of middle of ramus, rather than above 
middle ; symphysis both shorter and narrower than in H. amphibius, 
the longitudinal trough on its upper surface less well defined, the 
hinder border opposite front of middle premolar instead of from. 
of posterior premolar, the ratio of median length of symphysis to 
length of mandible (from articular process to front of alveolus of 
canine) about 27, instead of about 35. 

Teeth. — The teeth are essentially similar to those of Hippopota- 
mus amphibius, except that they are relatively smaller (transverse 
diameter of m 1 scarcely more than one-half that of palate) ; the 
crowns of the molars are narrower, and the outward curve of max- 
illary series behind premolars is more pronounced. 

Measurements. — Cranial measurements of type (millimeters) : 
Condylobasal length, 690 (730) ; 2 zygomatic breadth, 435 ± (435) ; 
rostral constriction, no (144) ; rostral expansion, 332 (370) ; occip- 
ital breadth, 278 (332) ; occipital depth (to basion), 196 (214) ; 
median depth between orbits, 181 (208) ; nasal, 390 (400) ; height 
of orbit, 75 (90) ; width of orbit, 70 (65) ; elevation of orbit above 
level of forehead, 24 (40) ; mandible (condyle to front of alveolus 
of canine), 587 (620) ; coronoid height, 355 (4 x o) ) canine width 
385 (403) ; length of symphysis (without median spine), 168 (224) ; 
maxillary toothrow (alveoli), 265 (258) ; mandibular toothrow, 293 
(286); first upper molar, 44.7x41.3 (45.5x45.5); second upper 



2 Measurements in parentheses are those of the adult male Zambezian skull 
(No. 123387). 



NO. 7 NEW SPECIES OE HIPPOPOTAMUS MILLER 3 

molar, 53.4x45.4 (51.0x50.8) ; first lower molar, 46.2x31.0 (51.4 
x 33.8) ; second lower molar, 59.0 x 35.4 (57.0x38.6); width of 
palate at anterior lobe of m 1 , 68.2 (76.2). 

Remarks. — At present there appear to be three well-marked species 
of Hippopotamus recognizable among the living members of the 
genus: (a) True Hippopotamus amphibius* of eastern and north- 
eastern Africa, (b) H. constrictus of Angola, and (c) H. australis* 
Duvernoy of the Cape region. The last I have not seen, but, so far 
as can be judged from the descriptions of Desmoulins and Duver- 
noy, it is a form in which the flattening of the cranium is carried 
even further than in H. constrictus, the orifice of the orbit is wider 
than high, and there are certain important peculiarities in the inter- 
relations of the upper and lower canines, and in the form of the 
anterior cheek-teeth. 



3 Synonymy : 

1758. Hippopotamus amphibius Linnaeus, Syst. Nat., I, 10th ed., p. 74 

(Nile). 
1846. Hippopotamus typus Duvernoy, l'lnstitut, XIV, p. 333. October 

7, 1846 ("Senegal or Abyssinia"). 

4 Synonymy : 

1846. Hippopotamus australis Duvernoy, l'lnstitut, XIV, p. 333. Octo- 
ber 7, 1846. (Previously described but not named by Desmou- 
lins, Journ. Physiol. Exp. et Path., V, p. 354, October, 1825.) 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54, NO. 7, PL. 1 




HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER 
HIPPOPOTAMUS CONSTRICTUS. TYPE 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54, NO. 7, PL. 2 




HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER 
HIPPOPOTAMUS CONSTRICTUS. TYPE 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54, NO. 7, PL. 3 




HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER 
HIPPOPOTAMUS CONSTRICTUS. TYPE 



•SMITHSONIAN MISCELLANEOUS COLLECTIONS 



VOL. 54, NO. 7, PL. 4 




HIPPOPOTAMUS AMPHIBIUS. ZAMBEZI RIVER 
HIPPOPOTAMUS CONSTRICTUS. TYPE 



D - 



SMITHSONIAN MISCELLANEOUS COLLECTIONS 

VOLUME 54, NUMBER 7 



DESCRIPTION OF A NEW SPECIES OF 
HIPPOPOTAMUS 

WITH FOUR PLATES 



BY 



GERRIT S. MILLER, Jr. 

Curator, Division of Mammals, U. S. National Museum 




(Publication 1927) 



CITY OF WASHINGTON 

PUBLISHED BY THE SMITHSONIAN INSTITUTION 

March 28, 1910 



LIBRARY OF CONGRESS 




005 492 436 7 






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